Aerial Communications Chooses DSET's Number Portability Solution

Bridgewater, NJ - February 14, 2000 - (NASDAQ: DSET) - DSET Corporation, a leading supplier of business-to-business e-commerce solutions for the telecom industry, announced today that wireless provider Aerial Communications, Inc. will employ DSET's Local Service Management System (LSMS) to update its ported-number database. Aerial's local number portability (LNP) database is used to complete calls to wireline numbers that have been ported to competitive local exchange carriers (CLECs). DSET's LSMS software application will support local number portability in combination with the MicroLegend SCCP Relay System that Aerial Communications has deployed to manage calls in its GSM network.

"DSET's credibility in the LNP market was critical to our decision to select their LSMS. We knew they could provide the turn-key solution we needed, along with all the professional services necessary for efficient deployment," said Ian Macpherson, Aerial's director of IN systems and roaming.

The chief benefit to Aerial Communications in deploying an LSMS is that it will be significantly more cost-effective to complete calls from its customers to ported wireline numbers. At present, numbers cannot be ported between wireless carriers. However, maintaining a ported-number database enables a wireless provider such as Aerial Communications to complete a call to a ported wireline number without having to pay another provider for the necessary call-routing information. Owning their own LSMS is a hedge against LNP database "dip" charges that would be assessed if Aerial customers' calls were routed to another carrier for the LNP database look-up.

"DSET LNP solutions are an established, integral part of wireline and wireless service in global markets," stated Paul Smith, DSET's senior vice president of strategic planning and product management. "Major network equipment vendors offer our LSMS as part of the products they sell to carriers worldwide. The sale of our LSMS application to Aerial Communications is another significant data point of success that validates DSET's expansion into the wireless market."

The DSET LSMS automates interconnection between carriers and the eight regional Number Portability Administration Centers (NPACs) that facilitate LNP in North America. DSET will also provide Aerial with an NPAC Simulator to test applications and equipment for conformance with LNP requirements.

The DSET LSMS can be used by wireline and wireless carriers to receive information about ported telephone numbers from one or more of the NPACs. This information is critical to the accurate completion of calls for customers who have changed their service to one of the new CLECs.

When a number is ported to a CLEC from an incumbent provider, the competitive carrier must forward certain LNP information to the appropriate NPAC. In turn, the NPAC sends related data to the LSMS of each carrier connected to it. The LSMS manages updates to the ported telephone-number database which is located in a signaling transfer point (STP) or service control point (SCP) in a carrier's SS7 network. These components control the delivery of services to businesses and homes within the public switched telephone network by maintaining up-to-date information on how to complete calls.

About Aerial Communications:

Headquartered in Chicago, Aerial Communications (NASDAQ: AERL) holds licenses to offer wireless personal communications services (PCS) in markets with a population of nearly 28 million in Ohio, Texas, Minnesota, Missouri, Pennsylvania, and Florida. The company is a majority-owned subsidiary of Telephone and Data Systems, Inc., which is also based in Chicago. Aerial is a member of the GSM Alliance, a consortium of North America's leading PCS companies. More information about Aerial can be found at www.aerial.com on the Web.

About DSET:

DSET Corporation is a leading provider of business-to-business e-commerce solutions for the global telecommunications marketplace. The DSET suite of electronic-bonding gateways is designed to interconnect the operations support systems (OSSs) of service providers that must exchange information and share network capabilities with trading partners to provision and maintain a growing range of services for customers in the competitive telecom market. DSET's local number portability solutions play a key role in enabling business and residential customers to change service providers without changing their local phone numbers. DSET is headquartered in Bridgewater, New Jersey, and the company's Web site can be viewed at www.dset.com.

Statements regarding financial matters contained in this press release, other than historical facts, are forward-looking. Since all statements about DSET's plans, estimates, and expectations are based on current projections that involve risks and uncertainties, and are subject to change at any time, the company's actual results may differ materially from expected results. Investors should consider these risks and uncertainties, which are discussed in documents filed by DSET with the Securities and Exchange Commission. These documents identify important factors that could cause the actual results to differ materially from those contained in the projections or forward-looking statements. DSET expressly disclaims any obligation to update any forward-looking statements.

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DSET Contacts:

Media Relations: Kathy Claxton, Corporate Marketing Communications Manager, 908-526-7500 Ext. 1280

Investor Relations: John P. Murphy, Westfield Investor Relations, 908-233-1558, e-mail: westfieldir@worldnet.att.net

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